MVA (Multi-domain Vertical Alignment)-driven liquid crystal display devices are widely known which realize wide viewing angles by dividing a liquid crystal layer into domains and changing the orientation into which liquid crystal molecules tilt from one domain to the other. Some liquid crystal display devices of this type incorporate a so-called “fish bone” pixel electrode. The electrode includes a plurality of stripe electrodes formed in a pattern that runs in different directions in different domains, and the stripe electrodes act as an alignment regulator for the formation of the domains used in MVA driving.
FIG. 18 represents a pixel arrangement for the liquid crystal display device, described in Patent Literature 1, which includes pixel electrodes including a plurality of stripe electrodes.
FIG. 18 shows a pixel formed in an area surrounded by two adjacent gate lines 2302 and two adjacent data lines 2303. There is provided a Cs line 2304 parallel to the gate line 2302 so as to divide the pixel area into upper and lower halves. A pixel electrode 2311 is provided in each of the upper half area 2311a and the lower half area 2311b. The two pixel electrodes 2311 are connected to each other by a pixel electrode 2312. The upper and lower pixel electrodes 2311 each include a cross-shaped electrode and a plurality of stripe electrodes which extend at angles from the cross-shaped electrode. The stripe electrodes extend in a different direction in each of the four regions formed by the cross-shaped electrode.
In the pixel electrode including the stripe electrodes, narrow slits (gaps between the stripe electrodes) as well as the stripe electrodes act as an alignment regulator, so that liquid crystal molecules can orient in the directions of a pattern when voltage is applied across the liquid crystal layer. This feature works as follows. Referring to FIG. 19, the liquid crystal molecules LCm on the stripe electrodes 101b tilt toward a stem of the cross-shaped electrode 101a (as opposed to toward a pixel edge 101e) under the influence of an electric field generated. The liquid crystal molecules therefore tilt in four different directions, one in each domain, when voltage is applied. The feature thus results in wide viewing angles.
The alignment regulation by use of stripe electrodes and narrow slits, however, does not yield sufficient electric field for regulation of orientation; the liquid crystal molecules fail to orient in a well-organized manner if voltage is applied abruptly across the liquid crystal layer. For this reason, in the manufacturing process, the voltage applied across the liquid crystal layer is changed slowly to achieve stable alignment of the liquid crystal molecules. PVA (polymer sustained alignment) is then performed on the liquid crystal molecules in such a condition. Polymer sustained alignment is a technique to blend liquid crystal with monomer which is subsequently light-irradiated or heated for polymerization, so that the polymer can preserve the pretilt angles of the liquid crystal molecules (see, for example, Patent Literatures 2 and 3).